[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: RE: [office-formula] serial number? Don't we mean serial date?
Rob, I mainly agree that there is no "type," Serial Day, but there are an incredible number of places where the current OpenFormula functions produce and accept Number values that are interpreted as serial-day values as part of the definition of those functions. I agree we should abstract this. But I don't think we can avoid talking about the serial-day interpretation of Number type values. There are also some quality matters to consider, such as what the minimal fraction of a day is that must be reliably represented and what the corresponding limitation on the span of serial days becomes for adequately-approximatable date-time and for exactly represented dates, respectively. - Dennis PS: I think epoch is an unfortunate choice, because it confuses the origin-date assigned to serial day 0 or serial day 1 in a mapping with what year 0 or year 1 of a given calendar system represents in terms of historical events. These strike me as independent. (Geological epochs we don't confuse with, one would hope.) THE USUAL ADDITIONAL THOUGHTS Many OpenFormula functions depend implicitly on the global origin-date/epoch value and the calendar mapping that goes with that origin date. This is true for anything involving a start-date and end-date parameter, especially YEARFRAC and anything that has time-period basis adjustments that depend on the actual calendar periods involved. We can't define these functions without acknowledging the existence of a mapping known to the implementation of the functions and talking about the dates those mappings correspond to. The DATEDIF function is a particularly interesting case of this interdependence. The other wrinkle is if there are mappings to and from text strings as part of OpenFormula itself. If any of those mappings involve date formats (not numbers), the issue shows up there too both for literals and string values received from references (although we could have an implementation finesse that case, just as for Logical/Number). [I don't recall seeing anything that would make or take a string holding a calendar date, but I am hedging my bet here.] -----Original Message----- From: email@example.com [mailto:firstname.lastname@example.org] http://lists.oasis-open.org/archives/office-formula/201001/msg00098.html Sent: Wednesday, January 27, 2010 11:46 To: email@example.com Subject: RE: [office-formula] serial number? Don't we mean serial date? This is really very simple. We don't need to refer to serial dates at all. There are dates and there are numbers. [ ... ]